we are using GPC for a coccyx wound. Is there a specific amount of time that is feasable or can it be used indefinitely? also note that the wound is noted to have recently began to tunnel. What would be the best kind of treatment to ask for? I don't think that a wound vac is a way to go...wound is too close to the rectum. Wound drainage(tunnelling) started yellowish-red and over 4 days is now a grayish color. C&S has been done ,results not in yet.